The South Korean COVID-19 vaccine cancer study recently made waves online after several social media figures and outlets claimed it “proved” a direct link between COVID-19 vaccination and an increased risk of cancer. But a deeper look into the research, its methodology, and the scientific terminology it used tells a completely different story — one that exposes how misinformation can distort legitimate science for viral impact.
Over the past week, various influencers and organizations have circulated alarming headlines suggesting that vaccines cause multiple forms of cancer, allegedly supported by new research from South Korea. However, the actual study — published in Biomarker Research, an open-access peer-reviewed journal — makes no such causal claim. In fact, its authors explicitly noted that their findings showed an epidemiological association without causal relationship, a key distinction that was conveniently ignored in online narratives.
How the Study Was Misrepresented
The controversy began when a study titled “1-year risks of cancers associated with COVID-19 vaccination: a large population-based cohort study in South Korea” was published. It analyzed a large dataset from South Korea’s national health insurance database to look for patterns in cancer diagnoses following vaccination.
What the researchers found was a statistical association — meaning that people who had been vaccinated were somewhat more likely to be diagnosed with certain cancers within one year. However, this did not mean that vaccines caused those cancers. The difference between correlation and causation is fundamental in epidemiology, and ignoring it leads to false and dangerous conclusions.
Nonetheless, several social media users seized on the results to spread sensationalized and misleading claims. One of the most prominent was Vigilant Fox, a self-described “independent media company” run by a former healthcare worker. The platform claimed the study showed a 27 percent overall increase in cancer risk due to COVID-19 vaccination, including a 53 percent rise in lung cancer and 69 percent increase in prostate cancer.
How Misinformation Spread Online
The distortion didn’t stop there. Nicolas Hulscher, who identifies as an “epidemiologist,” shared the study across multiple platforms, falsely claiming that vaccination increased the risk of seven types of cancer. He also connected it to unrelated studies to argue that “all cancers increased significantly after vaccination.”
Soon after, other figures with medical backgrounds amplified the misinformation. Peter A. McCullough, MD, PhD, whose controversial views on COVID-19 vaccines have drawn criticism before, tweeted support for the claim, gathering over half a million views. Similarly, Dr. Aseem Malhotra, a cardiologist known for promoting anti-vaccine narratives, described the South Korean study as “important and concerning,” giving unwarranted medical credibility to the false interpretation.
The organization Children’s Health Defense, led by anti-vaccine activist Robert F. Kennedy Jr., went further by publishing an article titled “All COVID Vaccines Increase Cancer Risk, New Study Concludes.” This headline was not only misleading but factually incorrect.
What the Study Actually Said
A fact-check by Al Jazeera’s Sanad Verification Agency revealed that all these claims omitted one crucial phrase: the study’s own disclaimer that its findings reflected “epidemiological association without causal relationship.”
This means the study identified a statistical pattern — vaccinated individuals appeared to have higher cancer diagnosis rates — but that pattern could be due to other unrelated factors, such as improved health monitoring, demographic differences, or coincidence.
In scientific research, such correlations often serve as the starting point for deeper investigation, not a conclusion of causation. The researchers did not claim vaccines cause cancer; rather, they documented an observation that may warrant further study into population health patterns.
To understand this clearly, experts often use a simple analogy: if ice cream sales increase in summer while drowning incidents also rise, it does not mean ice cream causes drowning. The two events are correlated because both are linked to warmer weather. Similarly, in this case, the observed rise in cancer diagnoses may be related to factors like healthcare access, post-pandemic screenings, or time-based coincidences — not vaccination itself.
Why Correlation Isn’t Causation
The misuse of epidemiological data is one of the most common ways misinformation spreads online. Correlation shows a relationship between two trends, while causation proves one directly leads to the other. Establishing causation requires controlled experimentation, eliminating confounding factors, and consistent replication of results across multiple independent studies — none of which apply to this South Korean research.
Medical experts emphasize that without biological evidence showing how vaccines could plausibly trigger cancer development, such claims are unfounded. COVID-19 vaccines have undergone extensive safety testing and real-world monitoring in billions of recipients, with no credible scientific evidence linking them to cancer.
Dr. William Moss, executive director of the International Vaccine Access Center at Johns Hopkins University, explained in a recent interview, “Correlation does not imply causation — it’s a statistical relationship that can be driven by a host of external factors. Anyone interpreting such a correlation as proof is either misunderstanding or deliberately misrepresenting science.”
How Disinformation Exploits Complexity
Misinformation campaigns often thrive on exploiting public unfamiliarity with scientific terms. The phrase “epidemiological association” sounds technical and can be twisted to appear as proof of danger when taken out of context. In this case, the distortion was amplified by influencers using professional titles — “doctor,” “epidemiologist,” or “health researcher” — to lend false credibility.
This tactic makes it difficult for the average reader to distinguish between legitimate medical commentary and pseudoscience. By framing the study as suppressed “evidence” of harm, misinformation actors create distrust in public health institutions and fuel vaccine hesitancy.
The Broader Impact of Vaccine Misinformation
False claims like these have real-world consequences. Since the beginning of the pandemic, misinformation about COVID-19 vaccines has been linked to lower vaccination rates, preventable deaths, and increased polarization around public health measures.
The World Health Organization (WHO) has called this phenomenon an “infodemic” — an overabundance of misleading or false information that spreads faster than verified facts. Studies show that even brief exposure to vaccine misinformation can significantly reduce public willingness to get vaccinated.
In this case, the misuse of the South Korean study risks reigniting vaccine fears that had begun to fade as the world moved past the pandemic’s worst phases.
Media Responsibility and Public Awareness
Fact-checking agencies and credible outlets have worked quickly to counter these claims. Sanad Verification Agency confirmed that the original authors of the study made no causal claim and that their work was misinterpreted by online commentators. Independent scientists reviewing the publication also noted that the dataset covered only one year — too short a timeframe to determine long-term cancer risk — and lacked biological evidence linking vaccination to cancer development.
For the media, this incident serves as a reminder of the importance of responsible reporting on scientific research. Headlines that oversimplify or exaggerate scientific findings can fuel panic and misinformation. Likewise, audiences are urged to read beyond viral posts and rely on verified, peer-reviewed information from trusted sources.
The Bottom Line
The South Korean COVID-19 vaccine cancer study does not prove vaccines cause cancer. It identifies statistical patterns without evidence of causation — a routine part of epidemiological analysis. The viral claims circulating on social media are misleading and have been debunked by multiple verification agencies.
Vaccines remain one of the most rigorously tested and monitored medical interventions in history, credited with saving millions of lives worldwide. Misrepresenting legitimate research to undermine them endangers public trust and health alike.
In an era where misinformation spreads faster than truth, understanding scientific nuance has never been more critical. The next time a viral claim seems alarming, it’s worth asking: What does the actual study really say?
Source: Al Jazeera
